5 Unclaimed Environmental Prizes

The X Prize is not a one-time thing. It's a whole foundation dedicated to giving millions of dollars to the best and the brightest of technological innovators in numerous fields, and it has turned its attention from space to Earth. The most recent X Prize aims to develop a car that can make a real dent in automotive greenhouse-gas emissions.

The Progressive Automotive X Prize is a joint effort between the X Prize Foundation and Progressive Insurance. They're offering $10 million to the people behind the best 100-mpg car.

It's not just about miles per gallon, though. The prize is about pragmatism as much as it's about environmentalism: This unbelievably fuel-efficient car has to be safe enough, smooth enough and cheap enough for mass consumption.

The X Prize knows how to draw attention to itself, which is part of its success. To win the $10 million, one car in each of two categories, mainstream and alternative, has to have the lowest overall time in two long-distance, urban road races planned for 2009 and 2010. The cars have to be as fast as they are Earth-friendly (or at least fast enough for typical highway driving -- we're probably not looking at Ferrari speeds here).

The mainstream winner must have a 200-mile (321-kilometer) range, while the alternative car has to last for 100 miles (160 kilometers) without refueling -- whatever "refueling" means in this context. Sixty teams from around the world have already signed up to compete.